Journal of Research in Environmental Health
Year:2025 | Volume:11 | Issue:1|Papers Count:8

Background and Purpose: Untreated dye-containing wastewater poses severe environmental hazards due to the persistence, toxicity, and resistance to biodegradation of dyes. This study aimed to evaluate the efficiency of catalytic ozonation using calcium peroxide (CaO₂) and titanium dioxide (TiO₂) to remove Acid Brown 14 from aqueous solutions. Materials and Methods: Laboratory-scale experiments were performed using a batch ozonation reactor. The influence of catalyst dosage, initial dye concentration, pH, and contact time on removal efficiency was assessed. Chemical oxygen demand (COD) was measured to evaluate dye degradation. Dye concentration was determined spectrophotometrically at 461 nm. Results: Optimal removal of Acid Brown 14 was achieved at pH 9, a contact time of 60 minutes, an initial dye concentration of 50 mg/L, and a catalyst dose of 0. 4 g/L, resulting in a decolorization efficiency of 97. 25%. Under these conditions, COD removal efficiency reached 58. 9% after 60 minutes. Conclusion: The findings confirm that CaO₂ and TiO₂ exhibit high catalytic activity in the ozonation process and represent promising agents for decolorising textile wastewater. Open Access Policy: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. To view a copy of this licence, visit https: //creativecommons. org/licenses/by/4. 0/

Background and Objective: Heavy metals enter water supply sources through various processes and, by entering the food chain and accumulating in tissues, can cause adverse health effects on humans. Therefore, this study aimed to determine the concentration of heavy metals in drinking water sources in Azadshahr city and assess the carcinogenic and non-carcinogenic health risks of the studied metals in this region. Material and Methods: This descriptive-cross-sectional study used instantaneous sampling from 10 water sources. The concentrations of heavy metals (arsenic, lead, cadmium, chromium, zinc, nickel, and copper) were measured using standard methods by atomic absorption spectrometry (ICP-MS). The human health risk assessment followed U. S. EPA-approved procedures. Environmental Protection Agency (EPA). Results: The results showed that the average concentrations of heavy metals (nickel, zinc, copper, lead, chromium, cadmium, and arsenic) were 0. 576, 0. 487, 0. 811, 0. 118, 23. 29, 0. 014, and 3. 466µg/L, respectively. Based on this, the highest and lowest average concentrations of heavy metals were related to chromium and cadmium, respectively. The results of the carcinogenic health risk assessment for all metals in adults and children were within the high-risk range. The hazard index (HI) for non-carcinogenic effects in adults was within the low-risk range for all sources, while for children, seven sources were in the low-risk range, and three sources were in the moderate non-carcinogenic risk range. Conclusion: In this study, the levels of arsenic and chromium metals were below the standard limit, but due to their high carcinogenic potential, the health risk assessment indicated a carcinogenic risk for both arsenic and chromium in both adult and children age groups. Therefore, we recommend regulatory units prioritize continuous heavy metal monitoring. Open Access Policy: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. To view a copy of this licence, visit https: //creativecommons. org/licenses/by/4. 0/

Background and Purpose: Heavy metals are recognized as highly hazardous pollutants, drawing significant attention from researchers, chemists, and biologists. This study, conducted in 2023, aimed to assess the contamination levels of cadmium (Cd), nickel (Ni), and vanadium (V) in the Alla River, potentially influenced by bitumen coating from the Qiramatin spring. Materials and Methods: Water samples were systematically collected from five stations, with three replicates per station, during summer (July) and winter (February). In total, 30 water samples were obtained across two seasons. Metal concentrations were measured using the Optima 8300 ICP-OES system (Perkin Elmer, USA). Results: The mean concentrations of Cd, Ni, and V in the Alla River water were 0. 89 mg L-1, 71. 16 mg L-1, and 8. 10 mg L-1, respectively. A comparison of the mean Cd (P=0. 041) and Ni (P=0. 022) concentrations between summer and winter revealed statistically significant differences (P<0. 05). However, seasonal variations in V concentration were not statistically significant (P>0. 05). The average concentrations of Cd, Ni, and V exceeded the permissible limits set by both the Iranian National Standard (No. 1053) and the World Health Organization (P<0. 05). Analysis of variance confirmed significant deviations of Cd (P=0. 034), Ni (P=0. 002), and V (P=0. 014) from the permissible limits established by the Iranian National Standard (No. 1053) (P< 0. 05). Conclusion: The elevated Ni and V concentrations at downstream stations suggest that bitumen contaminants entering the Alla River have adversely impacted water quality. Furthermore, assessments of the carcinogenic and non-carcinogenic risk indices for Cd, Ni, and V indicate that water consumption from this river poses potential health risks to humans. Open Access Policy: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. To view a copy of this licence, visit https: //creativecommons. org/licenses/by/4. 0/

Background and purpose: Rapid population growth, increased consumption, and the continuous rise in municipal waste generation pose significant challenges for modern urban society, necessitating a structured waste disposal strategy. Co-composting of organic waste has emerged as an effective method for treating multiple waste streams while mitigating the limitations of conventional composting. This study investigates key stabilization and maturity indicators in the composting process of organic waste and poultry manure. Materials and Methods: In this experimental study, organic waste was collected from a university cafeteria, poultry manure was sourced from the Ferdowsi University poultry farm, and sawdust, used as a bulking agent, was obtained from various urban locations. The composting process was monitored through 52 sampling events, assessing variations in physical (temperature, electrical conductivity (EC), organic matter content, and moisture), chemical (total organic carbon (TOC), total Kjeldahl nitrogen (TKN), C/N ratio, and pH), and biological (germination index (GI), total coliforms, and fecal coliforms) parameters across four 12-liter reactors. Weekly turning of the compost piles facilitated aeration. The poultry manure, organic waste, and sawdust ratios in reactors A1–A4 were 7. 6: 0: 2. 4, 7: 1. 5: 1. 5, 5: 3: 2, and 3: 6: 1, respectively. Final data analysis was conducted using SPSS 16. Results: Composting mass temperatures increased across all reactors following the loading process. The final organic matter content was lower in reactors A2 and A3 than the others. After 90 days, organic matter reduction ranged between 31. 5% and 36. 5% across all reactors. Final pH values varied from 7. 1 to 7. 9. EC increased in all reactors throughout the composting process, ranging between 4. 2 and 4. 84 dS/m. The C/N ratio progressively declined, reaching standard limits by the end of the composting process. Regarding the germination index, reactors A4, A3, A1, and A2 exhibited the highest seed root growth rates and germination indices. Conclusion: Findings indicate that week 10 marks all reactors' optimal compost maturity period. Reactors A3 and A4 demonstrated superior performance regarding the C/N ratio and GI. These results highlight co-composting poultry manure and municipal organic waste as a feasible, cost-effective, and sustainable approach for managing waste generated by university dining halls and poultry farms. Open Access Policy: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. To view a copy of this licence, visit https: //creativecommons. org/licenses/by/4. 0/

Background and Objective: Rapid socio-economic development has significantly increased municipal solid waste (MSW) generation. Several urban waste management strategies have been analyzed to address environmental impacts and evaluate energy-based sustainability. This study evaluates emergy-derived Environmental Yield Ratio (EYR) and net emergy across different waste treatment methods. Materials and Methods: A descriptive-analytical approach was applied. Emergy values for each input were calculated by converting physical quantities (mass, energy, monetary units) into standard emergy units using appropriate transformity factors. Stored emergy was also estimated. Emergy-based indicators were then derived to assess resource investment efficiency and potential for emergy recovery among waste management options. Results: Composting demonstrated Karaj's highest net emergy efficiency among the evaluated strategies. Emergy investment per gram of MSW was calculated as follows: sanitary landfill (6. 51 × 10⁶ sej/g), incineration (4. 61 × 10⁶ sej/g), and composting (8. 06 × 10⁵ sej/g). EYR and net emergy values confirm composting as the most environmentally favorable alternative. Conclusion: Emergy analysis indicates a direct relationship between higher EYR and increased net emergy. Composting outperforms sanitary landfilling in environmental performance, offering the most sustainable urban waste management solution for Karaj. Open Access Policy: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. To view a copy of this licence, visit https: //creativecommons. org/licenses/by/4. 0/

Background and purpose: One of the key indicators in discussions about air quality is the concentration of PM2. 5 particulate matter. This research employs a combined model that utilizes the maximum overlap discrete wavelet transform, variational mode decomposition, and backpropagation neural network (MODWT-VMD-BPNN). This two-stage decomposition technique aims to predict PM2. 5 levels in the city of Urmia. Material and Methods: Data on air quality in Urmia City, including levels of particulate matter (PM10 and PM2. 5), carbon dioxide (CO2), sulfur dioxide (SO2), nitrogen dioxide (NO2), and nitrogen monoxide (NO), were obtained from the General Directorate of Environmental Protection for the years 2019 to 2023. Meteorological data were sourced from the General Directorate of Meteorology of West Azerbaijan Province. In the first stage of the analysis, the original PM2. 5 data series was decomposed into two high-frequency detail levels (d1 and d2) and one low-frequency approximation level (a2) using the Maximum Overlap Discrete Wavelet Transform (MODWT) model. In the second stage, each of these detail and approximation levels was further decomposed into eight variable modes using the Variable Mode Decomposition (VMD) model. Subsequently, each variable mode was simulated and predicted using a backpropagation neural network (BPNN). To evaluate the accuracy and performance of the proposed model, it was compared with the MODWT-BPNN, VMD-BPNN, and standard BPNN models. Results: After reviewing the results, the MODWT-VMD-BPNN model achieved R=0. 92, RMSE=3. 8074, and MAE=2. 8582 during training, and R=0. 80, RMSE=2. 7679, and MAE=2. 1840 during testing, demonstrating superior accuracy and performance compared to the other models. Conclusion: The two-stage decomposition models tackle mode mixing effectively and enhance the extraction and prediction of multiple frequencies in PM2. 5 data with greater precision. Open Access Policy: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. To view a copy of this licence, visit https: //creativecommons. org/licenses/by/4. 0/

Background and Objective: Scented candles are a potential source of indoor air pollutants, particularly polycyclic aromatic hydrocarbons (PAHs), which are classified as hazardous environmental contaminants with significant health implications. These candles, widely used in households, religious and cultural ceremonies, spas, and other enclosed environments, can emit toxic compounds contributing to indoor air pollution and associated health risks. This study aims to evaluate the health effects related to exposure to PAHs released from scented candles and to provide recommendations for choosing safer alternatives. Materials and Methods: On February 15, 2023, a comprehensive literature review was conducted using databases such as PubMed, Web of Science, and Scopus, with relevant search terms related to scented candles and PAHs. Initially, 1, 297 records were retrieved. After removing duplicates, irrelevant, and non-English articles, 180 relevant studies were reviewed in full. From these, 11 high-quality and pertinent articles were selected and synthesized in this review. Results: The reviewed studies reveal that scented candles can emit multiple harmful substances, including volatile organic compounds (VOCs), particulate matter (PM), and PAHs. These pollutants have been linked to respiratory system disorders and an increased risk of carcinogenesis, particularly with chronic exposure. The findings highlight the urgent need for in situ monitoring and longitudinal health studies to better understand the long-term impacts of scented candle use. Conclusion: It is essential to conduct risk assessment and apply effective exposure reduction strategies regarding scented candle use. Suggested measures include opting for cleaner alternatives (e. g., soy or beeswax candles), minimizing burn duration, using candles with natural wicks, and improving indoor air ventilation. Increased public awareness and further toxicological and epidemiological research are critical to understanding and mitigating the health impacts of these commonly used indoor products. Open Access Policy: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. To view a copy of this licence, visit https: //creativecommons. org/licenses/by/4. 0/

Background and purpose: Heavy metal contamination in surface soils poses significant risks due to the potential for human exposure via inhalation, ingestion, and dermal contact. This study, conducted in 2022, assessed concentrations of arsenic (As), lead (Pb), cadmium (Cd), nickel (Ni), copper (Cu), zinc (Zn), cobalt (Co), and chromium (Cr) in surface soils surrounding Khuzestan Steel Company. Materials and Methods: Surface soil sampling was performed at 50 systematically selected stations around Khuzestan Steel Co. and one control station. A total of 50 composite samples, each with three replicates, were collected. Heavy metal concentrations were measured using a Varian AA220Z atomic absorption spectrometer (Australia). Results: In the area of Khuzestan Steel company, the highest average heavy metal values were for cobalt (13. 02 mg kg-1) and the lowest for cadmium (0. 02 mg kg-1). Cobalt and nickel values were higher than other metals in soil samples. The NIPI index for arsenic was 1. 95 within the range and 1. 84 outside the range, and for cobalt it was 1. 43 within the range and 1. 31 outside the range at low contamination levels, and for other heavy metals it was at a level without contamination. Environmental pollution indices, CF, Igeo, EF, and NIPI, indicate the absence of heavy metal contamination in the soils surrounding the Khuzestan Steel Co. Conclusion: Soil near Khuzestan Steel Co. exhibited variable heavy metal concentrations, with the highest levels observed for Co and the lowest for Cd. Pollution index results suggest that natural geological and climatic factors influence soil contamination more than anthropogenic sources. Open Access Policy: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. To view a copy of this licence, visit https: //creativecommons. org/licenses/by/4. 0/